The 'curled' structure is a fossil, certainly, but it is not a lizard. You can see enough of it to imagine it in 3D - and it is more cylindroidal in shape, or perhaps ovoid. The bit you see as a tail: that tapers off just because of how the rock has broken. The bit you see as an eye: that's just an accident of erosion (and if it was an eye, it would be in a distinct head - not the rounded end of the curled structure). The bit you see as a leg: that is significant, but it is not a leg (it is not jointed).

To some extent this looks like a cross-section of an echinoid, just off-centre. But the thickness of the shell is too great (there's a cross section at the top of this page, which includes bits corresponding to your 'leg' - http://www.bgs.ac.uk/discoveringGeology/time/Fossilfocus/echinoid.html). There is also no sign of the plates that make up an echinoid's shell.

Oystes can have shells thick enough to match your specimen, but I don't quite see that as the ID.